Identification guide to larvae of Caucasian Epeorus (Caucasiron) (Ephemeroptera, Heptageniidae) Author Hrivniak, Ľubos Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, 37005 Ceske Budejovice, Czech Republic & Faculty of Sciences, University of South Bohemia, Branisovska 31, 37005 Ceske Budejovice, Czech Republic lubos.hrivniak@gmail.com Author Sroka, Pavel Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, 37005 Ceske Budejovice, Czech Republic https://orcid.org/0000-0003-4367-6564 Author Bojkova, Jindriska Department of Botany and Zoology, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic Author Godunko, Roman J. Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, 37005 Ceske Budejovice, Czech Republic & Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12 / 16, 90237 Lodz, Poland https://orcid.org/0000-0003-2196-3327 godunko@seznam.cz text ZooKeys 2020 986 1 53 http://dx.doi.org/10.3897/zookeys.986.56276 journal article http://dx.doi.org/10.3897/zookeys.986.56276 1313-2970-986-1 CDFA38CA1B6F424D85246B540E63E954 2A3CD185EDDF52BDB0AD1E5DA924299B Epeorus (Caucasiron) soldani (Braasch, 1979) Figs 18 , 19 , 20 Iron soldani Braasch, 1979 Epeorus (Iron) soldani (Braasch, 1979); in Kluge (1988) Epeorus (Caucasiron) soldani (Braasch, 1979); in Kluge (1997b) Type locality. Russia, The Karachay-Cherkess Republic, western Greater Caucasus, Teberda (Glacier Alibek - stream, 1800-1900 m a.s.l.). Distribution. Georgia, south-western Russia. Species endemic to the Greater Caucasus (Fig. 18 ). Habitat. Larvae inhabit small streams and rivers at middle and high altitudes in the western and central Greater Caucasus. Frequently found above 1000 m a.s.l. Altitudinal range of sampling sites 426-1900 m a.s.l. (Fig. 18 ). Often syntopic with E. (C.) alpestris and E. (C.) sinitshenkovae . Main morphological diagnostics of larvae. (i) abdominal terga V-VII with well-defined triangular medial maculae (Fig. 19H, I ); (ii) abdominal sterna II-VI either without pattern or with indistinct pattern as on Fig. 19J, K ; (iii) setae on abdominal terga wide at base (Fig. 20E ); (iv) femora without medial hypodermal spot (Fig. 19F, G ); (v) tergum X without postero-lateral projections (Fig. 20L ); (vi) gill plates III with well-developed projection (Fig. 20G ); (vii) gill plates VII (in natural position of ventral view) narrow (Figs 19L ; 20H-K ); (viii) denticles along posterior margin of tergum VII relatively sparse and triangular (Fig. 20E ). Remarks. Taxonomy . This species was described based on male imago and larva from the western Greater Caucasus ( Braasch 1979 ). The type series is currently deposited in SMNS. Larva associated with imago based on the coloration of abdomen. Female imago not described. The lineage Caucasiron sp. 7 detected by Hrivniak et al. (2020b) is distributed in Georgia and morphologically corresponds to E. (C.) soldani . Therefore, E. (C.) soldani may represent a species complex. Figure 18. Geographical (left) and vertical (right) distribution of Epeorus (Caucasiron) soldani . Figure 19. Epeorus (Caucasiron) soldani , larva: A habitus in dorsal view B habitus in ventral view C habitus in lateral view D head of male in dorsal view E head of female in dorsal view F, G middle leg in dorsal view H, I abdominal terga J, K abdominal sterna II-VI L gills VII (in natural position from ventral view). Figure 20. Epeorus (Caucasiron) soldani , larva: A labrum (left half in dorsal view right half in ventral view) B incisors of left mandible C incisors of right mandible D setae on dorsal surface of femora E surface and posterior margin of abdominal tergum VII with detail of basally wide seta F gill I G gill III H gill VII (flattened on slide) I-K gill VII (in natural position from ventral view) variability in shape L abdominal segments VIII-X in lateral view M sternum IX of female.